[CDN/Maps] Update transformRequest to create absolute URLs (#179154)

## Summary

Fix #179058

Update the `transformRequest` function to create URLs that are callable
from inside workers that don't share the same domain.

Proposal is to to convert absolute path values to absolute URLs, e.g.
`/my/path` => `https://my.origin/my/path`.

- [x] Blocked by #178669

## Test locally with CDN

Easiest way to test is via the observability project built on this PR
(see buildkite output), otherwise:

- Build CDN assets (`node ./scripts/build.js --skip-docker-ubi
--skip-docker-ubuntu --skip-docker-fips --skip-os-packages`)
- Unpack the CDN assets
`target/kibana-8.14.0-SNAPSHOT-cdn-assets.tar.gz` and serve them `npx
http-server -p 1772 --cors --gzip --brotli`, remember to change the hash
dir name to `XXXXXXXXXXXX`
- Serve via different domain eg:
```
## My test
127.0.0.1 my.cdn.test
```
- Configure Kibana to load assets `server.cdn.url: http://my.cdn.test`

---------

Co-authored-by: Eyo Okon Eyo <[email protected]>
Co-authored-by: kibanamachine <[email protected]>

x-pack/plugins/maps/public/connected_components/mb_map/transform_request.test.ts

@@ -0,0 +1,34 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { transformRequest } from './transform_request';
+
+describe('transformRequest', () => {
+  let location: Location;
+
+  beforeEach(() => {
+    location = global.window.location;
+    // @ts-expect-error we need to set our own location value
+    delete global.window.location;
+    global.window.location = {
+      origin: 'https://transform.test.local',
+    } as unknown as Location;
+  });
+
+  afterEach(() => {
+    Object.defineProperty(global.window, 'location', { value: location });
+  });
+
+  it.each([
+    ['/internal/maps/fake/path', 'https://transform.test.local/internal/maps/fake/path'],
+    ['/', 'https://transform.test.local/'],
+    [' /with/space', 'https://transform.test.local/with/space'],
+  ])('converts %s to absolute URL', (input, output) => {
+    const { url } = transformRequest(input, 'Foo');
+    expect(url).toBe(output);
+  });
+});

x-pack/plugins/maps/public/connected_components/mb_map/transform_request.ts

@@ -14,14 +14,27 @@ import {
   MVT_GETTILE_API_PATH,
   MVT_GETGRIDTILE_API_PATH,
 } from '../../../common/constants';
-import { getHttp } from '../../kibana_services';
 
-const FONTS = getHttp().basePath.prepend(FONTS_API_PATH);
-const GETTILE = getHttp().basePath.prepend(MVT_GETTILE_API_PATH);
-const GETGRIDTILE = getHttp().basePath.prepend(MVT_GETGRIDTILE_API_PATH);
+/**
+ * This URL could be used from inside a Worker which may have a different base
+ * URL. This function takes a string that may be a path and converts it to an
+ * absolute URL.
+ */
+function prepareAbsoluteUrl(pathOrUrl: string): string {
+  pathOrUrl = pathOrUrl.trim();
+  if (pathOrUrl.startsWith('/')) {
+    return new URL(pathOrUrl, window.location.origin).toString();
+  }
+  return pathOrUrl;
+}
 
-export function transformRequest(url: string, resourceType: string | undefined) {
-  if (resourceType === 'Glyphs' && url.startsWith(FONTS)) {
+/**
+ * @param pathOrUrl - Assumed to be a full URL or a path starting with "/"
+ * @param resourceType - Indicator of what type of resource is being requested
+ */
+export function transformRequest(pathOrUrl: string, resourceType: string | undefined) {
+  const url = prepareAbsoluteUrl(pathOrUrl);
+  if (resourceType === 'Glyphs' && url.includes(FONTS_API_PATH)) {
     return {
       url,
       method: 'GET' as 'GET',
@@ -32,7 +45,7 @@ export function transformRequest(url: string, resourceType: string | undefined)
     };
   }
 
-  if (resourceType === 'Tile' && url.startsWith(GETTILE)) {
+  if (resourceType === 'Tile' && url.includes(MVT_GETTILE_API_PATH)) {
     return {
       url,
       method: 'GET' as 'GET',
@@ -43,7 +56,7 @@ export function transformRequest(url: string, resourceType: string | undefined)
     };
   }
 
-  if (resourceType === 'Tile' && url.startsWith(GETGRIDTILE)) {
+  if (resourceType === 'Tile' && url.includes(MVT_GETGRIDTILE_API_PATH)) {
     return {
       url,
       method: 'GET' as 'GET',